With the WIFI being widely used in mobile phones, industries and users have higher and higher requirements on WIFI performance, especially on the WIFI's adaptability to multi-application scenarios and conditions, and some operators have adopted their own guidelines. The WIFI performance is a very important indicator of high-end mobile phones, and it affects the overall performance of a mobile phone and determines the product's success or failure.
At present, the way for controlling WIFI power in a mobile phone is too simple, wherein, generally a nominal power is used to transmit, or it is to transmit indirectly with a certain duty cycle, in this frequent transmitting/receiving transmission mode, constant power transmission brings great challenges to the mobile phone's power consumption, meanwhile, high-power transmission for a long time has some radiation to the human body, and how to design a power control that adaptively adjusts the WIFI step by step based on the WIFI signal strength, the mobile phone's WIFI throughput requirements, and the user's individual demand is a problem that has not been solved yet for the WiFi.
Meanwhile, due to the instability of an internal Power Amplifier (PA) provided in the WIFI chip, the fluctuation of the maximum output power is generally about plus or minus 3 DB, and the fluctuation of the peak power is 5 DB, for the maximum peak power, it can reach 24 DB, and the power output stability has much randomness and a controllable method is needed to make specific adjustments on the actual user power.
Secondly, due to differences in single-board devices and the matching, and the differences in the WIFI calibration, the consistency requirements on the single-board WIFI performance of different batches of boards as well as boards from different manufacturers cannot be changed. The WIFI target transmit powers of different mobile phones may vary widely, how to self-adjust to achieve secure and stable operating power is also a challenge for the production and calibration of each mobile phone, even if the WIFI of each terminal is calibrated and tested in detail, it cannot guarantee that the power of the user's mobile phone is precisely controllable.
Moreover, because there are more and more multimedia functions in the mobile phone, while the battery power supply of the terminal is limited, the long time working of WiFi at a constant power makes the phone usage time largely shortened, and the power consumption is increased rapidly and the terminal will be heated up severely, because the temperature of the phone chip increases, the clock frequency drift increases, and the stability and transmission rate of the WIFI connected terminal will be affected.
In WIFI actual uses, powers in different channels and at different rates will also be different, and the power amplitude will directly affect the key factor, error vector magnitude (EVM), in the transmission performance, and the modulation and demodulation performance of a mobile phone with poor EVM performance will be affected, thereby affecting the channel quality and downloading speed of the WIFI.
Currently, there are the following kinds of mobile phone WIFI power adjustment circuits: 1. internal calibration, control and adjustment; 2. external coupling back, adjustment and control; 3. Direct output no power control. The abovementioned power adjustment result is that the WIFI power is called and output as a constant power in a signaling mode after the calibration, and the power is constant, the accuracy is poor, and the matching is also inconsistent for parasitic capacitors from different manufacturers, which is not conducive to a single adjustment, and does not have the adaptive accurate adjustment capability.